1. Field of the Invention
The present invention relates generally to the field of printed circuit boards. More particularly, the present invention relates to multi-level printed circuit boards (or “PCBs”) that integrate optical data communications with other boards without electrical connections. That is, the present invention relates to backplane circuit boards that integrate photonic connection.
2. Background Information
Today, much of the world's communication is carried on optical fibers, the data encoded in modulated light. Transmission rates are measured in billions of bits per second, until the data reaches its destination. There, the light is converted into electrical impulses so that it may be routed electronically. The result is lower data rates and increased delay.
Opto-electronic devices are being developed that incorporate waveguide structures on silicon substrates allowing for integration of light buses and electrical buses. These integrated devices will replace discrete components and make the transition from photon streams to electron streams more efficient and/or eliminate the transition altogether. Clearly, the ultimate efficiency will be achieved when no conversion from light to electrical signals is required, thus enabling communication as light from source to destination.
One of the impediments to achieving this objective is the backplane. The backplane is the interconnecting point for devices in a system and may be passive or intelligent. Typically, devices (sometimes referred to as “daughter boards”) are plug into a backplane through mechanical means. Additional cabling may be required to interconnect devices to each other or other points on the backplane resulting in slower data transfer rates, increased opportunities for failure, and increased costs. Opto-electronic devices require an electrical and/or an optical interface to the backplane.
Typically, backplanes and daughter boards are constructed on printed circuit boards (PCBs) on to which discrete components are mounted. What is needed are daughter-boards and backplanes constructed from PCBs that have both electrical and optical interfaces so as to eliminate additional cabling and to reduce or eliminate the need to convert from light signals to electrical signals. Such PCBs would also incorporate passive components such as multiplexers, de-multiplexers, transducers and interferometers to effect optical signaling.